Nipple valve



FIG. 1 is a plan view showing a preferred embodiment of a nipple valve of the invention;

FIG. 2 is a side view in elevation of one side of the nipple valve of FIG. 1 (the other side would be a mirror image and need not be shown);

FIG. 3 is a bottom view of the nipple valve of FIG. 1;

FIG. 4 is an end view of the nipple valve of FIG. 1; and,

FIG. 5 is an end view opposite to that shown in FIG. 4. 

The ornamental design for an nipple valve, as shown and described. 